Liquid crystal display devices that use liquid crystals and plasma display devices that use plasma have found practical application as flat and thin display devices.
A liquid crystal display device provides a backlight, and displays images by altering an array of liquid crystal molecules by application of voltage, passing or blocking light from the backlight. Additionally, a plasma display device causes a plasma state to occur by application of voltage to a gas that is enclosed within a panel, and ultraviolet light produced by energy occurring on return from the plasma state to the original state becomes visible light through irradiation of a fluorescent body, displaying an image.
Meanwhile, in recent years, development has been progressing for self-illuminating type displays employing organic electroluminescent (EL) elements in which the element itself emits light when voltage is applied. When the organic EL element receives energy by electrolysis, it changes from a base state to an excited state, and at the time of return from the excited state to the base state, the difference in energy is emitted as light. The organic EL display device is a display device that displays images using these organic EL elements.
A self-illuminating type display device, unlike a liquid crystal display device, which requires a backlight, requires no backlight because the elements themselves emit light, and thus it is possible to make the structure thin compared to a liquid crystal display device. Additionally, because motion characteristics, viewing angle characteristics, color reproduction performance, and the like are superior to a liquid crystal display device, organic EL display devices are attracting attention as next-generation flat and thin display devices.
However, the light-emitting characteristics of the organic EL element deteriorate if the voltage continues to be applied, such that the luminance diminishes even if the same electric current is input. This means that in a case where light is emitted very frequently from a specific pixel, the light-emitting characteristics of the specific pixel will deteriorate more than those of other pixels, giving rise to a problem that is known as the burn-in phenomenon.
The burn-in phenomenon can also occur in the liquid crystal display device and the plasma display device, but because those display devices display images by applying alternating current voltages, they require units that regulate the voltages that are applied. In contrast, in the self-illuminating type display device, a method is used that compensates for the burn-in by controlling the amount of electric current. Patent Document 1 is an example of a document that discloses a technology for that compression for the burn-in in the self-illuminating type display device.
Patent Document 1: Japanese Patent Application Publication JP-A-2005-275181